Vaisesika Sūtra 7.2.17

असति नास्तीति च प्रयोगात् ॥१७॥

asati nāstīti ca prayogāt ॥17॥

[असति (asati) - when not existing; न अस्ति (na asti) - it does not exist; इति (iti) - thus; च (ca) - and; प्रयोगात् (prayogāt) - from usage;]

When not existing, it is termed 'nāstī', i.e. does not exist, as well.